1. Field of the Invention
This invention relates to a vehicle door lock apparatus and more particularly to a vehicle door lock apparatus for locking and unlocking a door by remote operation.
2. Description of the Related Art
A vehicle door lock apparatus receives and interprets a signal transmitted from a small-sized transmitter excellent in portability and locks or unlocks a door. For example, upon reception of a lock request signal from the transmitter, the vehicle door lock apparatus places a door lock mechanism in a lock state; on the other hand, upon reception of an unlock request signal from the transmitter, the vehicle door lock apparatus places the door lock mechanism in an unlock state. Thus, the vehicle door lock apparatus enables the user to use the transmitter to lock and unlock the door from a location at a distance from the vehicle and offers high convenience to the user and thus becomes widely available.
The following two types are available as lock systems of vehicle door lock apparatus in related arts: Type a wherein the door lock mechanism is placed in a lock state only when all doors are closed and type b wherein the door lock mechanism is placed in a lock state regardless of whether doors are open or closed.
For the driver to lock doors by remote operation using the transmitter, usually the driver opens the door on the driver's seat side, gets off the vehicle, and closes the door and then uses the transmitter to transmit a lock request signal.
By the way, if a fellow passenger exists in the passenger seat or the rear seat and gets off the vehicle together with the driver and both the fellow passenger and the driver leave the vehicle, the driver needs to check that the fellow passenger gets off the vehicle and the doors on the passenger seat side and the rear seat side are closed before using the transmitter to transmit a lock request signal.
With the vehicle door lock apparatus of the type a, the door lock mechanism is placed in the lock state only if all doors are closed (namely, if one door is open, none of the doors are placed in the lock state) and therefore if the transmitter is operated for transmitting a lock request signal before the fellow passenger closes the door on the passenger seat side, the doors are not locked.
On the other hand, with the vehicle door lock apparatus of the type b, the door lock mechanism is placed in the lock state regardless of whether doors are open or closed. However, most front-door lock mechanisms adopt self-cancel (if the door lock mechanism is placed in the lock state and then the door is closed, the door is not locked) and thus if the transmitter is operated for transmitting a lock request signal before the fellow passenger closes the door on the passenger seat side, although the door lock mechanism on the passenger seat side is once placed in the lock state, the lock state is released when the door is closed, and therefore the door on the passenger seat side is not locked.
Thus, if a fellow passenger exists, the driver needs to check that all doors are closed before operating the transmitter; it is extremely irksome for the driver.
JP-A-5-156851 (official gazette 1) and JP-A-9-72137 (official gazette 2) disclose means for solving the problem. Official gazette 1 discloses an apparatus of the type wherein a portable transmitter and a vehicle-installed receiver are provided each with a transmission-reception circuit, a very faint search signal is transmitted periodically from the vehicle-installed receiver, and when the transmitter receives the search signal, it returns an ID code and when the vehicle-installed receiver receives the ID code, the doors are unlocked; in contrast, when the vehicle-installed receiver does not receive the ID code, the doors are locked.
According to the apparatus disclosed in official gazette 1, if the driver carrying the transmitter leaves the vehicle, the transmitter becomes unable to receive the search signal from the vehicle-installed receiver and does not return the ID code. That is, the doors of the vehicle are automatically locked if the driver carrying the transmitter simply leaves the vehicle without operating the transmitter.
Therefore, if a fellow passenger exists, the need for the driver to check that all doors are closed is eliminated and thus the inconvenience of operation can be eliminated.
However, in the invention disclosed in official gazette 1, the transmitter and the vehicle-installed receiver need to be provided each with the transmission-reception circuit and there is a problem of complicating the configuration and increasing the costs.
On the other hand, official gazette 2 discloses an apparatus of the type wherein when all doors are closed, if a lock request is received from a portable transmitter, doors are locked; on the other hand, when any door is open, if a lock request is received, the doors are locked at the point in time when all doors are closed by the time a predetermined time has elapsed.
According to the apparatus disclosed in official gazette 2, if a fellow passenger exists, the driver need not wait for all doors to be closed before operating the transmitter and further the need for providing the transmitter and the vehicle-installed receiver each with the transmission-reception circuit as in the apparatus disclosed in official gazette 1 is not involved, so that a vehicle door lock apparatus that can eliminate the inconvenience of operation in a comparatively simple configuration can be provided.
However, the apparatus disclosed in official gazette 2 involves the risk of confining the transmitter in the cabin. For example, if the driver opens the door on the driver's seat side in attempting to get off the vehicle and then operates the transmitter to transmit a lock request signal with the door open, the door is locked at the point in time when the driver closes the door regardless of whether or not the driver holds the transmitter.
Thus, if the driver closes the door with the transmitter left in the cabin after operating the transmitter, the transmitter is confined in the cabin.
When the door on the driver's seat side is open, if the driver operates the transmitter in the cabin by mistake, gets off the vehicle, and closes the door with the transmitter left in the cabin without being aware of operating the transmitter, the transmitter is also confined in the cabin.